Amazon is said to be considering opening 3,000 of its cashierless stores by 2021.

The tech giant already has four locations of its Go stores up and running, but it may have up to 10 locations open by the end of the year, with as many as 50 by 2019, Bloomberg reported, citing sources close to the situation.

Example - Amazon - E-commerce - Cloud - Computing

It would mark the latest example of Amazon's rapidly growing e-commerce, cloud computing and, now, advertising empires - as the firm's online advertising business gets closer to overshadowing the likes of Google and Facebook.

Amazon opened its first cashierless store in Seattle two years ago and has launched two additional locations in Seattle and another in Chicago.

Firm - Challenge - Stores - Cost - Technology

The firm's main challenge to opening more stores is the high cost of the technology used to power the cashierless design, as well as other hardware.

Its first location in downtown Seattle cost over $1 million in hardware, according to Bloomberg.

Amazon - Cost - Hardware - Increase - Profit

Amazon could reduce the cost of hardware and increase profit margins by focusing on selling prepared foods, instead of offering an expanded selection of grocery items.

CEO Jeff Bezos has weighed whether the stores should offer prepared foods and limited grocery items, akin to a 7-Eleven, or if they should offer prepared sandwiches, soups and other items like a Pret a Manger.

Amazon - Go - Stores - Amazon - Chains

By rolling out 3,000 Amazon Go stores, Amazon would quickly become one of the biggest chains in the US, Bloomberg said.